USP6-induced neoplasms: the biologic spectrum of aneurysmal bone cyst and nodular fasciitis  André M. Oliveira, MD, PhD, Margaret M. Chou, PhD  Human Pathology  Volume 45, Issue 1, Pages 1-11 (January 2014) DOI: 10.1016/j.humpath.2013.03.005 Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 1 Anteroposterior radiograph of the distal forearm in a skeletally immature patient shows an eccentric, osteolytic lesion with a narrow zone of transition, intact peripheral shell of bone, and a benign buttress of periosteal new bone formation proximally. The imaging features are typical of ABC (kindly provided by Doris E. Wenger, Department of Radiology, Mayo Clinic, Rochester, MN). Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 2 A, ABC is macroscopically hemorrhagic and multicystic. B, This appearance is reflected in low-power magnification. C and D, The fibrous septa are characterized by a proliferation of bland spindle cells intermixed with occasional multinucleated giant cells and immersed in a fibromyxoid matrix. C, A peculiar blue bone formation is often seen and may be diagnostically useful. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 3 NF is composed by bland spindle cells immersed in a fibromyxoid matrix. Notice that this lesion may show a variety of histologic patterns that have been associated with the duration of the lesion. A, In the initial phases, NF tends to be more myxoid. Later on, the lesion becomes more cellular (B) and eventually more fibrotic and hyalinized (C and D). D, Notice the hemorrhagic foci and microcystic formation. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 4 Partial karyogram showing the chromosomal translocation t(16;17)(q22;p13) in ABC. This translocation results in the formation of the fusion gene CDH11-USP6. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 5 Diagram showing the overall structure of USP6 fusion genes in ABC and nodular fasciits. A common theme is the fusion of exon 1 or 2 of the promoter donor genes to the entire coding sequence of USP6. Notice several CDH11-USP6 splice variants, many of which can be detected in the same tumor. TBC, Tre2/Bub2/Cdc16 domain; UBP, ubiquitin-binding protein domain. *Two splice variants of ZNF9 have been identified. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 6 Model of USP6 oncogenic function in ABC. USP6 fusion genes result in USP6 overexpression because of promoter swapping mechanism. Aberrant USP6 expression interferes with the normal osteoblastic maturation by inhibiting bone BMP4 and stimulating gremlin-1. At the same time, USP6 induces inflammation, neovascularization, osteolysis and matrix degradation through nuclear factor κB activation and secretion of MMP-9. This model is consistent with the “granulation-tissue” appearance and cystic formation seen in NF and ABC. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 7 A, FISH showing rearrangement of the MYH9 locus (separation of green and red signals) in an example of NF. B, Dual-FISH shows juxtaposition of the USP6 and MYH9 loci (3′ USP6 labeled in spectrum green and 5′ MYH9 labeled in spectrum orange). Mouse NF-like tumor induced by USP6-transfected preosteoblasts (C) and human NF (D). Notice the similar histologic features. Interestingly, this xenograft was initially designed to simulate ABC cells, a finding that supports the idea that ABC and NF belong to the same spectrum of neoplasms (from Erickson-Johnson et al [10]). Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 8 Kaplan-Meier curves for local recurrence-free survival show no difference in the clinical course for primary ABC with or without USP6 fusion genes (from Oliveira et al [50]). Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 9 Sequential FISH staining in G-banded slide showing rearrangement of the USP6 locus in a case of NF. Notice the separation of the red and green probes on the derivative chromosomes 17 and 22, respectively. This rearrangement is of difficult recognition in a regular G-banding analysis. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions

Fig. 10 NF (A) and ABC (B) show histologic similarities that have been underappreciated, especially considering their occurrence in distinct clinical contexts. It is possible that these 2 lesions belong to the same spectrum of neoplasms. Human Pathology 2014 45, 1-11DOI: (10.1016/j.humpath.2013.03.005) Copyright © 2014 Elsevier Inc. Terms and Conditions